1. Field of the Invention
The present invention relates to a display device, and more particularly to a hold-type display device and a driving method thereof.
2. Description of the Related Art
In recent years, with the prevalence of liquid crystal display devices, there has been an increasing need for improved display quality.
One display quality problem which needs improvement is gray scale displaying performance. Specifically, liquid crystal display devices have problems in that their gray scale reproducibility is not sufficient. In order to solve this problem, a method for enlarging the dynamic range of an input image signal while also adjusting the luminance of a backlight is proposed in, for example, Japanese Laid-Open Patent Publication No. 2002-108305.
There is also a problem in that the display quality is likely to depend on the ambient brightness. In answer to this problem, a method which adjusts the luminance of a backlight in accordance with ambient brightness is proposed in, for example, Japanese Laid-Open Patent Publication No. 10-20277.
However, even by using the methods described in the aforementioned laid-open publications, it may still be difficult to obtain a sufficient display quality. The reason is that, since the luminance range of a cold-cathode tube which is generally employed in a backlight is limited to about 10% to 100%, there is a limit to the dynamic range of gray scale (luminance) levels which can be reproduced.
This problem is not just true to liquid crystal display devices, but is common to any hold-type display device that is equipped with a backlight. Furthermore, there is also a desire for improvement in the gray scale displaying performance of hold-type display devices of a self-emission type not requiring a backlight, e.g., organic EL display devices.